To be honest I've noticed the "dump you at a random point on the page or right back at the top" feature of Firefox, I've always wondered if it was a cookie issue and if I cause it having cookies restricted. At least I know I'm not alone with that one
As to the bookmark bar bouncing I have mine hidden so I don't know if it does it, I'll have it on view when I get home to see if it does it there, will let you know if it does.